The separation of ethyl acetate from methyl ethyl ketone has heretofore presented considerable difficulty by reason of the fact that the boiling points of these two compounds is only 2.4.degree. C. apart. This requires the use of fractionating columns containing a large number of plates and a high reflux ratio in order to obtain separation of these two compounds at an acceptable purity. Ethyl acetate and methyl ethyl ketone frequently occur together in manufacturing processes, thus posing an important separation problem. While separation is multiplate fractionating columns is the current preferred method, it is a costly step. For instance, to separate ethyl acetate from methyl ethyl ketone into two fractions each possessing a purity of 99%, it requires a column comprising a minimum of 118 theoretical plates.
A number of investigators have described methods for separating ethyl acetate from methyl ethyl ketone using azeotropic distillation. These include U.S. Pat. No. 2,703,783 to Harrison et al; U.S. Pat. No. 2,607,719 to Eliot et al and U.S. Pat. No. 2,528,761 to Lake et al.
U.S. Pat. No. 3,404,186 to Bailey et al describes the separation of methyl ethyl ketone (MEK) from ethyl acetate (EA) by hydrolyzing the methyl ethyl ketone-ethyl acetate fraction and recovering ethanol and methyl ethyl ketone. Water is added to the mixture and the methyl ethyl ketone is extracted with a hydrocarbon and the ethanol recovered in the water. U.S. Pat. No. 2,862,853 to Luke, Jr. et al describes an aqueous extractive distillation of methyl ethyl ketone and ethyl acetate fraction in a distillation of methyl ethyl ketone and ethyl acetate fraction in a distillation column. This procedure can be used to separate part of the ethyl acetate present from methyl ethyl ketone but will not provide a commercially pure methyl ethyl ketone, i.e., as high as 99% purity.
The presence of water will produce azeotropes with the ethyl acetate and methyl ethyl ketone in the ethyl acetate-methyl ethyl ketone mixtures which are extremely difficult to break and will not provide a substantial separation of the ethyl acetate from the methyl ethyl ketone.